New Phaser Design - “Causality 4” – Built with you in mind!

[Mark Hammer]

Rick, I´ve been following this thread, will build one eventually.
Regarding new features, I always thought that the usual triangle / whatever wave for modulating was quite boring, so, why not make a more interesting LFO? Sequenced a la seek wah, two parallell LFO´s, another LFO modulating the main LFO, envelope controlled LFO speed or depth, etc etc... just my personal ideas.

Great work!

Hi Morocotopo,

Your idea is good - I have tried one which is probably similar in the sounding result : 2 phasers paralleled with different rates. I discovered that it was the way was obtained the miraculous viola/violin tones on my old Crumar Multiman I , and certainly on Elkas too.

A+!

Having as many phasers as I do (not bragging, just an admission of a sickness!), I can vouch for the pleasing quality of applications which feel less periodic or cyclical in nature.  There are several ways to achieve this.

1) One phase-shift path, modulated by one master source, derived from mixed sources.  Those could be more than one LFO, or random+LFO.  One my Boss RPH-10, I modded it to have envelope following mixed in with LFO modulation, so you can "push" the effective sweep range higher (or lower) by playing harder.

2) One phase-shift path, but separate chunks of it (in series) modulated by separate independent sources.

3) Several parallel phase shift paths, each separately modulated, but arriving at the same common mixing stage with the clean signal.

4) Several clean+allpass sections, run in parallel.

5) Several clean+allpass sections (i.e., complete phasers), run in series.

And, departing from the normal, briefly.....

6) A series of phase-shift stages modulated by source A, and additional stages in the feedback loop, modulated by source B.

Of course, all of this is multiplied by the assorted waveform variations.  Let's say we have a 4-stage/step analog sequencer providing 4 continuously adjustable repeating CVs.  That gets set to a slow speed, with no glide, just a pure stairstep, and gets mixed in with a "normal" triangular or similar LFO waveform, set for modest sweep width.  That combination should get you a normal-sounding sweep that keeps shifting ranges.  Of course, set the sequencer for faster speed, and the LFO for medium speed, and you'll end up with something approximating a quasi-random S&H sound.

Or you can get ALLweird, and build one or more of John Blacet's DPG units, that were originally devised to sweep the Blacet Phase-filter.
http://www.blacet.com/dpg1.jpg
http://www.blacet.com/dpg2.jpg

[soggybag]

I have always wanted to build the DPG. I bought enough parts for two about ten years ago. I started one and got it about half way. At the time my skills were not that great, so I stopped, thinking I would get back to it in the future.

[Pigyboy]

Hi All,
Will a NE5517AN work in place of the LM13700? It is supposed to be a direct replacement. I am just getting the parts together for this for a friend.
Hey Rick, did you consider this:

Casuality may be a misspelling of:

    * Casualty, a person who is killed or injured in a war or disaster
    * Causality, the relationship between cause and effect
    * Casual, the characteristic of being informal

Hate to be nit picky but....

[Skruffyhound]

But it is number 2, isn't it? Causality.
I've seen at least one built as a "Casualty" though.

[frequencycentral]

Yeah, it's always been Causality to me.    It seemed to make sense at the time, phase shift being the cause, phasing being the effect. And 4 because there are four stages of cause, the effect being cumulative. But I am aware of some folks who think/thought that it's Casualty. Why would anyone call a phaser Casualty? Ok, I guess a non working build would be a casualty. I'm currently laying down plans for my Causality Modular..............

[Pigyboy]

That what I love about you Rick you even invent new words. I just ran through the thread trying to nail down the 5 pot values. Where do I look?
Thank you all,
Chris

[frequencycentral]

That what I love about you Rick you even invent new words. I just ran through the thread trying to nail down the 5 pot values. Where do I look?
Thank you all,
Chris

The MkII schematic with all the pot values can be found on page 6: http://www.diystompboxes.com/smfforum/index.php?topic=80456.msg680532#msg680532

[Pigyboy]

Thank you Rick

[Govmnt_Lacky]

Rick,

Reading over the thread and seeing that there is a "unity" issue. Can a 100K linear pot be added to the build in place of R12 to manually adjust the output volume level? Could this be a 6-knob Causality?

[frequencycentral]

Rick,

Reading over the thread and seeing that there is a "unity" issue. Can a 100K linear pot be added to the build in place of R12 to manually adjust the output volume level? Could this be a 6-knob Causality?

Yes you can do that I guess. But it's probably better to just use a trimmer instead. I can't see the value in having a volume knob on a phaser. I did a layout including space for a trimmer, if you look at the gut shot of my last build a couple of pages back you'll see the trimmer. I'll post that layout a little later.

[Govmnt_Lacky]

Yes you can do that I guess. But it's probably better to just use a trimmer instead. I can't see the value in having a volume knob on a phaser. I did a layout including space for a trimmer, if you look at the gut shot of my last build a couple of pages back you'll see the trimmer. I'll post that layout a little later.

Hey Rick,

I looked over the layout you have on Page 7. I see that R12 is installed however I do not see a spot for a trimmer. Is this the latest layout that is on this thread now? If not, then your offer to post the trimmer version of the PCB layout would be much appreciated!
Thanks as always  

[Mark Hammer]

The Retro-Sonic phaser ( http://www.tonefactor.com/prodimages/retrophaser.jpg ) includes a level control.  It allows for adjustment from somewhat lower than bypass (for those who wish to engage the phaser for rhythm sections) to somewhat higher than bypass (for those who wish to use the phaser for solos), without going full off.  I did the same thing for one of my Ropez pedals, and it can be useful, though obviously not to everyone.

[frequencycentral]

Here's the latest layout, just the addition of the blue pads for a trimmer instead of R12. I spaced it for the specfic size of trimmer I usually use. I'm also working on a layout for a Causality 6, with 4 OTA stages instead of 2, and following Mark Hammer's advice for implementation of the extra stages. I'll try to include pads for a few different trimmer sizes in that layout.

[Govmnt_Lacky]

Thanks Rick. Cannot wait to get this one on a PCB!

One last question about the Speed pot. As per the layout, I know that Lug 2 is on the right. Which lug is connected to the left pad? Lug 1 or Lug 3 for proper Speed control?


Thanks a ton! 

[frequencycentral]

Speed lugs are 2 and 3. Just leave lug 1 with no connection, or connect it to lug 2.

[frequencycentral]

Based on Mark Hammer's addition of 2 extra stages to his build, I've made a new layout for "Causality 6" - as yet unverified, and it could do with a set of sharp eyes to check it for errors.......

Features:

• 2 extra OTA stages that can (optionally) be switched in or out via a DPDT.
• Provision to add even more stages.
• Pads for wet only mod.
• Optional odd/even stages in the regen path (parity switch).
• Input section options (R38, C12/R37)
• Polarity protection (D3).
• Pads to fit pretty much any size trimmer in the VR1 position.

This is a little speculative. I'm assuming the extra stages will work as shown, and that the parity mod will do also. My experience tells me that it will. I'm planning to use two of these PCBs for my super-duper-semi-modular Causality when I eventually get around to it.

The original Causality 4 board was 20 x 22 pads, the Causality 6 is 21 x 25 pads, just a bit bigger - nice job Rick!. It should still fit in a 1590B, though a 1590BB build will be easier, especially if all the options are incorporated.

As is customary, I am happy to receive any PCBs that folks might want to send my way!  

[Pigyboy]

First you always make me laugh. Second, don't get hurt patting yourself on the back. And, I am just getting ready to make boards for the 4 so I will try to get a transfer of the 6 and make it with the others. I will let you build the 6 while I hurdle the 4.
"Dammit Jim, I am not a miracle worker!"

[Xide88]

For what you add VR1? What is purpose of it?

Sorry for my bad english 

[frequencycentral]

For what you add VR1? What is purpose of it?

Sorry for my bad english 

So you don't have to trust what my idea of unity gain is, you can fine tune it yourself. Or....

The Retro-Sonic phaser ( http://www.tonefactor.com/prodimages/retrophaser.jpg ) includes a level control.  It allows for adjustment from somewhat lower than bypass (for those who wish to engage the phaser for rhythm sections) to somewhat higher than bypass (for those who wish to use the phaser for solos), without going full off.  I did the same thing for one of my Ropez pedals, and it can be useful, though obviously not to everyone.

....so you could instead rig it up as a panel mounted control, if that's your bag.

[Mark Hammer]

Absolutely.  Of course, panel space is always precious, so think through whether it is a needed feature first.